cracked screen on HTC Aria

So I had my phone under a week, and I dropped it while bending over(less than 2 feet from the group), and the screen cracked. I'm an att customer-have been forever.

I decided that I should buy the insurance online-which you can do up to 30 days after purchasing the phone. But not sure if this will cover my cracked screen. I also dont know how long I should wait to try to turn in my phone, or if they accept you right away.

I also don't know if I buy a screen from somewhere else and putting it on would void my warrenty.

Also-I want a good case for this phone, something where if I dropped it, it would be safe-not those stupid "screen protectors" which do nothing.